Soft tissue response in orthognathic surgery patients treated by bimaxillary osteotomy: cephalometry compared with 2-D photogrammetry

Does Clockwise Rotation of Maxillomandibular Complex Using Surgery-First Approach to Correct Mandibular Prognathism Improve Facial Appearance?

BACKGROUND

Facial aesthetics may be optimized based on a deeper understanding of soft tissue changes after orthognathic surgery.

PURPOSE

The purpose of the study was to delineate facial soft tissue changes after clockwise rotation (CWR) of the maxillomandibular complex (MMC) to correct mandibular prognathism using the surgery-first approach.

STUDY DESIGN, SETTING, SAMPLE

This prospective cohort study enrolled patients over 18 years of age with skeletal Class III malocclusion in the craniofacial center. The patients were excluded with previous history of craniofacial syndrome, orthognathic surgery trauma, infection at surgical sites, chin deviation (menton deviation ≥4 mm), 2 or more missing data points after surgery, or without informed consent. This study compared significant facial changes before (T0) and after orthodontic debonding (T1) in the CWR and control groups.

PREDICTOR VARIABLE

The patients were divided in accordance with maxillary occlusal plane change (OPC) after surgery into CWR (OPC >4°) and control (OPC ≤4°) groups.

MAIN OUTCOME VARIABLE

The primary outcome variable was frontal lip curvature (FLC: Right Cheilion-Stomion-Left Cheilion, degree) with or without upper lip curving upward at T1, where upper lip curving upward was considered more favorable.

COVARIATES

The covariates included age, sex, and various cephalometric measurements.

ANALYSES

The Mann-Whitney U test, paired, and independent t-test were implemented to compare the intragroup and intergroup differences. Statistical significance was indicated by P value <.05.

RESULTS

The study comprised 34 patients (21 women) in the control group and 37 (29 women) in the CWR group; their mean ages were 23.64 ± 4.38 and 24.21 ± 3.84 years, respectively (P value = .562). At T1, the CWR group had significant increased FLC (P value = .001), alar width (P value = .034), and lower vermilion height (P value = .018), and decreased lower lip length (P value = .004). The high FLC group had significant decreased upper lip projection (P value = .002) and increased nasolabial angle (P value = .013). The significant relationship between CWR and high FLC was supported by the χ2 test (P value = .018) and multiple logistic regression (P value = .017).

CONCLUSION

Greater CWR of the MMC increased FLC and lower vermilion height and reduced lower lip length. High FLC resulting from the CWR of the MMC improved facial appearance by moving the upper lip curve upward.

Assessment of soft- and hard-tissue changes following combined anterior segmental bi-jaw orthognathic surgery

Background

Anterior segmental Bi-jaw orthognathic surgery is indicated primarily for the correction of dentoalveolar protrusion. They are also indicated for correcting apertognathia, closing interproximal spaces between segments and can be incorporated with other osteotomies to obtain better results.

Aim

The aim of this study was to analyze and compare the soft- and hard-tissue changes in patients who underwent combined anterior segmental bi-jaw orthognathic surgery.

Settings and Design

To compare and evaluate soft- and hard-tissue changes before and after combined anterior segmental bi-jaw orthognathic surgery by assessing (a) parameters in vertical dimension and (b) parameters in horizontal dimension and patient satisfaction was also assessed following surgery at 6 months' time interval.

Materials and Methods

It is a prospective, single center and analytical study with sample size of 20 patients. It required routine setup for orthognathic surgery and manual tracing of lateral cephalograms. The surgical outcomes were assessed by hard tissue (Sella Nasion Point A (SNA) angle, Sella Nasion Point B (SNB) angle, Point A Nasion Point B (ANB) angle, NAPg, U1-NF, L1-MP angles; NA, NB, B-Pg, Nasion-Anterior nasal spine (N-ANS) distance, Anterior nasal spine-Gnathion (ANS-Gn) distance, and overjet and overbite) and soft tissue (facial convexity, NL, LM angles; LM fold, UL and LL protrusions, Upper lip length (ULL), Lower lip length (LLL), Sn-A, Si-B, Pg-Pg*, Ls-U1, Li-L1 distances, interlabial gap, and U1 exposure) variables pre and postsurgery.

Statistical Analysis

Descriptive statistics involved the mean and standard deviation, and recorded data were subjected to the statistical analysis using IBM SPSS 20 statistical package. The paired t-test, Pearson correlation coefficient were used. The level of significance P < 0.05 was taken as statistically significant and P < 0.01 as very significant.

Results

Overall improvement after surgery in both hard- and soft-tissue parameters was observed and significant changes were seen in every variable, except Si-B (P > 0.05). Correlations between soft- and hard-tissue changes were significant in both sagittal and vertical planes. Patients' satisfaction score showed that all patients had the high overall rate of satisfaction.

Conclusions

Our study concludes that combined anterior segmental bimaxillary orthognathic surgery is a simple technique with minimal postoperative complications and limited relapse. The changes in facial esthetics and occlusion following orthognathic surgery depend highly on the stability achieved during the postoperative period.

A Preliminary Study of a Novel Reference Plane of the Head: Comparing With the True Horizontal Plane

A new reference plane of the head, based on soft tissue landmarks and suitable for clinical analysis and soft tissue measurements, is needed. We recently discovered a novel reference plane, that is, the COs plane, which was formed by bilateral Lateral Canthus and bilateral Otobasion Superius and might be horizontal at the natural head position (NHP). In this study, we investigated the angles between the COs plane and the true horizontal (TrH) plane while sitting and standing, aiming to explore whether the new plane could be used as a substitution for the reference plane in clinical practice. Briefly, 26 volunteers were enrolled. Their sitting and standing NHP were recorded using the 3dMDface system. In the pitch axis, the mean angle of COs/TrH was 0.29 degrees and 0.41 degrees for sitting and standing positions, respectively, showing no statistical difference ( P >0.05). However, in the roll axis, the mean angle of COs/TrH for sitting position and standing positions was 1.08 and 1.33 degrees ( P <0.05), which was considered to be the result of habitual canting of the head. Moreover, there were no significant differences between the sitting and standing NHP, considering the COs/TrH angles ( P >0.05). To sum up, we concluded that the COs plane could be used as a reliable reference plane in certain soft tissue analysis and clinical applications.

Cephalometric evaluation of soft tissue changes following Anterior Maxillary Osteotomy setback in Southern Dravidian population

Introduction

Anterior Maxillary Osteotomy (AMO) is one of the commonly done orthognathic surgical procedure in maxilla. Though a lot of research have been done in the Caucasian population regarding soft tissue changes after AMO, there are only few studies for the southern Dravidian poplation. The purpose of this study was to evaluate the soft tissue changes in association with AMO setback in the southern Dravidian population

Materials and methods

The study included a series of 10 patients of age group 20–40 years who underwent AMO. Lateral cephalograms were taken for each patient 2 weeks before and 6 months after the surgery. Three parameters namely, nasolabial angle, upper lip protrusion and interlabial gap were used to evaluate the soft tissue changes.

Results

Mean values of pre and post-surgery were taken for nasolabial angle, upper lip protrusion and interlabial gap and were compared. Soft tissue changes in all the three parameters were found to be statistically significant.

Conclusions

From the limited evidence of the study, it can be concluded that soft tissue changes following AMO setback in southern Dravidian population and the Caucasian population are almost similar.

Changes in the facial soft tissue profile after maxillary orthognathic surgery

Objectives

To compare the changes of the soft tissue profile in relation to the displacement of the underlying hard structures in maxillary orthognathic surgery and to contribute to the esthetic prediction of the facial profile after surgical procedures.

Materials and methods

We analyzed the sagittal changes in the facial soft tissue profile related to surgical changes in skeletal structures after maxillary osteotomy in a retrospective study. The study sample comprised 115 adult patients between the ages of 18–50 years who had undergone maxillary orthognathic surgery and interdisciplinary orthodontic treatment at the Department of Orthodontics, Ludwig-Maximilians University of Munich, Germany. LeFort I osteotomy cases in both maxillary monognathic and bignathic osteotomy procedures were included. All subjects had received rigid fixation. A cephalometric analysis of presurgical and postsurgical cephalograms was performed and the correlations between hard tissue and soft tissue change ratios were evaluated using a bivariate linear regression analysis. A vertical line through the landmark sella (S) perpendicular to the nasion-sella line (NSL) served as the reference plane.

Results

The subnasale (Sn) followed the A point (A) by 57%, the soft tissue A point (A′) followed the A point (A) by 73% and the upper lip, represented by the landmark labrale superius (Ls) followed the upper incisor (Is) by 73%; all three in a linear correlation with a mean prediction error of nearly 2 mm.

Conclusion

The scatterplots show a linear correlation with a wide spread for all three pairs of reference points. The wide spread and the high prediction error of almost 2 mm indicate low predictability of the expected lip position and Sn.

Analysis of facial features and prediction of lip position in skeletal class III malocclusion adult patients undergoing surgical-orthodontic treatment

OBJECTIVES

This study presents a retrospective study aimed to analyze the facial features at each stage of surgical-orthodontic treatment for skeletal class III malocclusion, and predict the changes in the lips after treatment.

MATERIALS AND METHODS

There were 49 skeletal class III malocclusion patients treated with bimaxillary surgery and orthodontic treatment enrolled in this study. Lateral cephalograms were obtained before treatment (T0), 1 month before surgery (T1), 1 month after surgery (T2), and after debonding (T3) for cephalometric measurements. After the measurement of the required variables, paired t-test, Pearson's correlation analysis, and multiple linear regression were performed using SPSS 19.0.

RESULTS

The main factors associated with changes in the upper lip included ΔUIE-V, ΔA-V, ΔU1A-V, and ΔL1A-V, and those associated with changes in the lower lip included ΔLIE-V, ΔL1A-V, ΔB-V, ΔPog-V, and Δfacial angle. The predicted regression equation for the horizontal change in the upper lip was represented as ΔUL-vertical reference line (VRL) = 9.430 + 0.779 (ΔUIE-VRL) - 0.542(VULT) (P < 0.05) with a mean error of 1.04 mm; the corresponding equation for the lower lip was ΔLL-VRL = -1.670 + 0.530 (ΔB-VRL) + 0.360 (Ls-E) + 0.393 (ΔLIE-VRL) (P < 0.05), with a mean error of 1.51 mm.

CONCLUSIONS

This study explored the relationship between orthognathic surgery and changes in the lips and obtained the predictive equations of lip position after treatment by using multiple linear regression, which likely offers a reference for prediction of soft tissue changes before surgical-orthodontic treatment in patients with skeletal class III malocclusion.

CLINICAL RELEVANCE

The findings can help dentists to rapidly predict the lip changes after surgical-orthodontic treatment in patients with skeletal class III malocclusion. The study has been registered with the Chinese Clinical Trial Registration (No: ChiCTR1800017694).

Midfacial Advancement Line-A Comparative Evaluation of a New Measurement Method in Orthognathic Surgery

PURPOSE

In planning intraoral quadrangular Le Fort II osteotomy (IQLFIIO), simulation of hard and soft tissue changes will be important at the infraorbital, Le Fort I, and incisor level. The aim of our study was to evaluate a new method for visualization and quantification.

MATERIALS AND METHODS

Three different methods of quantification were compared: the point-to-point (PTP) measurement, which has been viewed as the reference standard; part comparison analysis (PCA); and a new method, the midfacial advancement line (MFAL) measurement. We performed a measurement comparison study using the Bland-Altman method to measure agreement and enrolled patients with midfacial deficiency and Class III malocclusion who had undergone IQLFIIO. The primary predictor variable was the method of measurement. The primary outcome variable was the amount of midfacial advancement. We also investigated the time required, visualization quality, and interobserver agreement.

RESULTS

The sample included 12 subjects with a mean age of 21.6 years; 7 patients were male. The PTP and MFAL showed no significant observer dependence. The advancement measured with PTP and MFAL showed no significant differences. However, the advancement measured using MFAL and PCA showed a significant difference. The highest rating of visualization was found for MFAL. The time requirements were similar for all 3 methods.

CONCLUSIONS

Our results have shown that the MFAL is a suitable method for visualization and quantification of soft and hard tissue changes at all 3 face levels in 1 image. It could be a valuable tool for virtual planning of midfacial advancement surgery.

[Establishment of three-dimensional measurement methods of nasolabial soft tissue for patients with maxillary protrusion]

OBJECTIVE

To establish a series of three-dimensional measurement methods of nasolabial soft tissue for maxillary protrusion patients by using 3dMD camera, and to evaluate preoperative and postoperative changes of the nasolabial soft tissue.

METHODS

Three-dimensional facial photos of 30 female patients with maxillary protrusion [average age, (27.33±2.54) years] were taken by 3dMD camera preoperatively and at the end of postoperative 6 months or more. Then, 3dMD patient software was used to locate the selected landmarks at nasolabial region on the three-dimensional photos. Ten measurements, including soft tissue line distance, angle, curve distance and postoperative three-dimensional volume changes were measured twice with one week interval by 3 investigators, respectively. A standard consistency test calculated by the correlation coefficients (ICC) was performed between two sets of data (including all of the 10 measurements) for each investigator and among the three investigators to verify the repeatability.

RESULTS

The average maxillary incisor retraction distance of the 30 subjects was (5.13±0.99) mm, and the average follow-up time was (11.07±5.11) months. The standard consistency test was performed between the two sets of data for each investigator, and the correlation coefficients (ICC) of the 10 measurements were all over 0.8 for each investigator (P>0.05). The standard consistency test was performed among the three surveyors, with the result that the ICC of the width of the bilateral inner canthus, the height of the nose, the height of nasal tip, nasolabial angle, philtrum length, the curve height of upper vermilion and the height of upper lip were greater than 0.8 (P>0.05), and the ICC of the distance between SbalSbal, length of nasal dorsum and three-dimensional volume change of upper lip were 0.680, 0.627 and 0.528, respectively (P>0.05).

CONCLUSION

3dMD camera and 3dMD patient software can be used to measure and analyze the three-dimensional morphology of the nasolabial soft tissue for patients with maxillary protrusion preoperatively and postoperatively, and it is relatively accurate and reliable. However, the repeatability of three-dimensional positioning of the nasal tip point and the Sbal is slightly worse resulting in the lower value of the ICC of the distance between SbalSbal and length of nasal dorsum, as well as the upper lip three-dimensional volume change after the operation.

[Establishment of three-dimensional measurement methods of nasolabial soft tissue for patients with maxillary protrusion]

OBJECTIVE

To establish a series of three-dimensional measurement methods of nasolabial soft tissue for maxillary protrusion patients by using 3dMD camera, and to evaluate preoperative and postoperative changes of the nasolabial soft tissue.

METHODS

Three-dimensional facial photos of 30 female patients with maxillary protrusion [average age, (27.33±2.54) years] were taken by 3dMD camera preoperatively and at the end of postoperative 6 months or more. Then, 3dMD patient software was used to locate the selected landmarks at nasolabial region on the three-dimensional photos. Ten measurements, including soft tissue line distance, angle, curve distance and postoperative three-dimensional volume changes were measured twice with one week interval by 3 investigators, respectively. A standard consistency test calculated by the correlation coefficients (ICC) was performed between two sets of data (including all of the 10 measurements) for each investigator and among the three investigators to verify the repeatability.

RESULTS

The average maxillary incisor retraction distance of the 30 subjects was (5.13±0.99) mm, and the average follow-up time was (11.07±5.11) months. The standard consistency test was performed between the two sets of data for each investigator, and the correlation coefficients (ICC) of the 10 measurements were all over 0.8 for each investigator (P>0.05). The standard consistency test was performed among the three surveyors, with the result that the ICC of the width of the bilateral inner canthus, the height of the nose, the height of nasal tip, nasolabial angle, philtrum length, the curve height of upper vermilion and the height of upper lip were greater than 0.8 (P>0.05), and the ICC of the distance between SbalSbal, length of nasal dorsum and three-dimensional volume change of upper lip were 0.680, 0.627 and 0.528, respectively (P>0.05).

CONCLUSION

3dMD camera and 3dMD patient software can be used to measure and analyze the three-dimensional morphology of the nasolabial soft tissue for patients with maxillary protrusion preoperatively and postoperatively, and it is relatively accurate and reliable. However, the repeatability of three-dimensional positioning of the nasal tip point and the Sbal is slightly worse resulting in the lower value of the ICC of the distance between SbalSbal and length of nasal dorsum, as well as the upper lip three-dimensional volume change after the operation.

Clinical performance of occlusal onlays made of lithium disilicate ceramic in patients with severe tooth wear up to 11 years

OBJECTIVES

Evaluation of survival and complication rate of monolithic occlusal onlays made of lithium disilicate ceramic used in patients with severe tooth wear up to 11years of clinical service.

METHODS

In a prospective non-randomized clinical study 7 patients (4 male, 3 female; median age: 44.3±6.56years old) were restored full mouth with a total of 103 adhesively bonded occlusal onlays made of lithium disilicate ceramic (IPS e.max Press, Ivoclar Vivadent, Schaan, Liechtenstein). All restorations were examined during annual recall visits using periodontal parameters according to the modified United States Public Health Service (USPHS) criteria: (a) marginal discoloration, (b) secondary caries, (c) marginal integrity, (d) surface texture, (e) restoration fracture, and (f) occlusal wear, rating with Alpha, Bravo and Charlie over an observation period up to 11years (68-139 months; median: 94.9±26.1 months). Data was statistically analyzed using the Kaplan-Meier estimation.

RESULTS

Monolithic lithium disilicate occlusal onlays presented a 100% survival rate. Four restorations within one patient (3.9%) presented marginal discoloration, one after 60 and three after 108 months (all rated Bravo). One restoration (1%) showed a marginal crack formation (technical complication) after 120 months, rated Bravo. No biological complication, debonding or secondary caries could be found and tested periodontal parameters showed excellent results.

SIGNIFICANCE

Based on the analyzed data up to 11years, monolithic occlusal onlays made of lithium disilicate ceramic can be considered as a reliable treatment option for full-mouth rehabilitations in patients with severe tooth wear.

Changes in the facial soft-tissue profile after mandibular orthognathic surgery

OBJECTIVES

To investigate the correlation between soft- and hard-tissue changes after mandibular orthognathic surgery, to generate precise prognostic values for the esthetic treatment outcome of the facial profile.

MATERIAL AND METHODS

In this retrospective study, sagittal changes in the facial soft tissue profile in relation to surgical changes in hard structures after mandibular osteotomy were examined. The sample population included 144 reported adult patients aged 17-50 years who had received combined mandibular orthognathic surgery and orthodontic treatment at the Department of Orthodontics, Ludwig-Maximilians University of Munich, Germany. Both mandibular advancement and mandibular setback cases in monognathic and bignathic osteotomy procedures were included. All subjects had undergone rigid fixation. A cephalometric analysis of presurgical and postsurgical cephalograms was performed, and the correlations between hard-tissue and soft-tissue change ratios were evaluated using a bivariate linear regression analysis.

RESULTS

The lower lip, represented by the landmark Labrale inferius (Li), followed the lower incisor (Ii) by 77%. The soft-tissue B-point (B') followed the B-point (B) by 97% and the soft-tissue Pogonion (Pg') followed the Pogonion (Pg) by 97% in a linear correlation.

CONCLUSION

The scatterplots show a distinct linear correlation and no significant difference in the direction of the movement. A wider spread for the lower lip (Li/Ii) indicates a lower predictability of the expected lip position, whereas a narrow spread of the chin values (B'/B and the Pg'/Pg) reveals a very good predictability of the postoperative chin position.

CLINICAL RELEVANCE

This study contributes valid data for the soft-tissue profile prediction in orthognathic surgery.

Soft Tissue Changes Measured With Three-Dimensional Software Provides New Insights for Surgical Predictions

PURPOSE

Although computer-aided craniofacial reconstructions allow for simulation of hard tissue changes, the prediction of the final soft tissue facial changes remains a challenge. The purpose of the present study was to evaluate the 3-dimensional (3D) soft tissue changes in patients undergoing 2-jaw orthognathic surgery.

PATIENTS AND METHODS

For the present retrospective cohort study, 40 consecutive patients (11 men and 29 women; mean age 23.5 ± 4.9 years) who had undergone 2-jaw orthognathic surgery were selected. We obtained the medical and dental records from 3 weeks before surgery and 6 months after surgery. We used image processing software to segment, superimpose, and quantify the hard and soft tissue displacements in 3 dimensions before and after surgery at 15 paired locations. The soft tissue and hard tissue changes were determined through quantification of homologous landmark displacements between the preoperative and postoperative computed tomography data. We measured the 3D soft and hard tissue changes and the anteroposterior, inferosuperior, and transverse components of the changes. We quantified the ratios between the soft and hard tissue changes, tested Pearson's correlation between these changes, and developed a predictive regression equation for the observations at each location.

RESULTS

We found that soft tissue movement followed the hard tissue movement, with a correlation nearly equal to 0.9 (range 0.85 to 0.98), suggesting that in general the soft tissues of the maxillary and mandibular landmarks are affected similarly by the skeletal movements. The anteroposterior component of the soft tissue 3D displacements followed the hard tissue movement with a ratio greater than 0.9 and with high correlation (r > 0.9) in the mandible.

CONCLUSION

The results of the present study provide surgeons with a ratio of hard to soft tissue change and the strength of the correlations, which will allow for more accurate 3D predictions for both midline and lateral structures in bimaxillary orthognathic surgical cases. In addition, predictive equations for various landmarks were developed and can be used in computer-based prediction programs to aid in treatment planning of soft tissue changes.

Influence of maxillary advancement surgery on skeletal and soft-tissue changes in the nose - a retrospective cone-beam computed tomography study

Objectives

Surgical correction of skeletal maxillary retroposition is often associated with changes in the morphology of the nose. Unwanted alar flaring of the nose is observed in many cases. The aim of the present study was therefore to investigate the influence of surgical advancement of the maxilla on changes in the soft-tissue morphology of the nose. Having a coefficient that allows prediction of change in the nasal width in Caucasian patients after surgery would be helpful for treatment planning.

Materials and methods

All 33 patients included in this retrospective study were of Caucasian descent and had skeletal Class III with maxillary retrognathia. They were all treated with maxillary advancement using a combination of orthodontic and maxillofacial surgery methods. Two cone-beam computed tomography (CBCT) datasets were available for all of the study's participants (16 female, 17 male; age 24.3 ± 10.4 years): the first CBCT imaging was obtained before the planned procedure (T0) and the second 14.1 ± 6.4 months postoperatively (T1). Morphological changes were recorded three-dimensionally using computer-aided methods (Mimics (Materialise NV, Leuven/Belgium), Geomagic (Geomagics, Morrisville/USA)). Statistical analysis was carried out using SPSS 21 for Mac.

Results

The mean sagittal advancement of the maxilla was 5.58 mm. The width of the nose at the alar base (Alb) changed by a mean of + 2.59 mm (±1.26 mm) and at the ala (Al) by a mean of + 3.17 mm (±1.32 mm). Both of these changes were statistically highly significant (P = 0.000). The increase in the width of the nose corresponded to approximately half of the maxillary advancement distance in over 80 % of the patients. The nasolabial angle declined by an average of −6.65° (±7.71°).

Conclusions

Maxillary advancement correlates with a distinct morphological change in nasal width. This should be taken into account in the treatment approach and in the information provided to patients.

Changes in cephalometric variables after orthognathic surgery and their relationship to patients' quality of life and satisfaction

OBJECTIVES

This study was designed to assess the relationship between postsurgical cephalometric changes and quality of life and satisfaction after orthognathic surgery.

MATERIAL AND METHODS

Sample size consisted of 30 patients with class III and 25 patients with class II malocclusion treated with bilateral sagittal split osteotomy and Le Fort I osteotomy. Profile convexity, lower facial height proportion, lip position and length, nose, and chin position were measured on pre and post-treatment cephalograms. To assess the patients' satisfaction and quality of life (QoL) after surgery, the questionnaire of the Rustemeyer's study and Oral Health Impact Profile (OHIP) questionnaire were used, respectively. The paired-sample t-test, Spearman correlation analysis and Pearson correlation analysis was used in SPSS statistical software.

RESULTS

In class III malocclusion patients, decrease in facial angle, convexity angle, mentolabial angle, and increase in upper lip protrusion had the most positive impact on QoL. Decrease in facial angle and increase in upper lip protrusion were correlated positively with satisfaction questionnaires. In class II malocclusion patients, increase in convexity angle, facial angle and mentolabial angle had the most positive impact on satisfaction and QoL.

CONCLUSIONS

Consideration both subjective and objective parameters affecting on the patients' satisfaction and their quality of life is essential.

A better statistical method of predicting postsurgery soft tissue response in Class II patients

OBJECTIVE

To propose a better statistical method of predicting postsurgery soft tissue response in Class II patients.

MATERIALS AND METHODS

The subjects comprise 80 patients who had undergone surgical correction of severe Class II malocclusions. Using 228 predictor and 64 soft tissue response variables, we applied two multivariate methods of forming prediction equations, the conventional ordinary least squares (OLS) method and the partial least squares (PLS) method. After fitting the equation, the bias and a mean absolute prediction error were calculated. To evaluate the predictive performance of the prediction equations, a leave-one-out cross-validation method was used.

RESULTS

The multivariate PLS method provided a significantly more accurate prediction than the conventional OLS method.

CONCLUSION

The multivariate PLS method was more satisfactory than the OLS method in accurately predicting the soft tissue profile change after surgical correction of severe Class II malocclusions.